Compensating device for watch balances



June 6, 1944. R. STRAUMANN 2,350,838

COMPENSATING DEVICE FOR WATCH BALANCES Filed April 30, 1942 Fig.1 v M a .1, V I II I- Patented June 6, 1944 COMPENSATING DEVICE FOR WATCH BALANCES Reinhard Straurnann, Waldenburg, near Basel, Switzerland Application April 30, 1942, Serial No. 441,194 In Switzerland February 4, 1942 4 Claims.

It is known, that the regulation of the temperature-coefiicient of the oscillating system of watch movements, motors or the like, of the type having a self-compensating, ferro-magnetic oscillating spring can be effected by way of magnetic influence.

The object of the present invention is a device of the above known kind, which is characterized by the fact that it comprises seats arranged in one or more groups or rows in the neighbourhood of the oscillating spring for the reception of magnetic elements, the magnetic strength or action of which is determined in advance in view of the correction of a compensating error of a known value, with regard to a certain position which is given by said seats, so that the regulation of the oscillating system can be effected by a number of such magnetic elements which are determined in advance.

Advantageously, the seats for the reception of the magnetic elements are realized in form of tap holes provided in the gear plate, whilst the magnetic elements are formed by magnetic screws.

In the following there is described with reference to the accompanying drawing, an example of the deivce according to the present invention.

Fig. 1 is a vertical section of the oscillating system of a pocket watch, and

Fig. 2 is a plan View corresponding to Fig. 1 with parts broken away.

Fig. 3 is a fragmentary detail view, in section, showing a modification.

In the drawing, a. is a self-compensating ferromagnetic spiral spring and b is the balance of the oscillating system of a watch movement. is the watch gear plate provided with one of the bearings d of the balance axis. The watch plate 0 is also provided with a plurality, for instance seven, tap holes 6, arranged on a concentric arc with regard to the balance axis. In five of these tap holes e are screwed magnetic compensating screws J. Tests have shown that five screws having a magnetic strength of two oersted each will suflice to change the thermo-elastic coefficient of the oscillating system from 1 sec./l/24 hours to -0.08 sec./1/24. hours. Without the compensating screws 1 the compensating error of the watch was +1 sec./l/24 hours. Thus, it is possible to reduce a determined compensating error for instance from +0.8 sec./1/24 hours to zero by screwing into the tap holes e four screws f. Accordingly, by screwing into the tap holes a determined number of magnetic screws having each a determined magnetic strength, the regulation of the temperature-coefficient can be effected rapidly and in a safe manner without tests by just one single adjusting operation.

If desired, the watch plate 0 could be provided with a second group or row of tap holes which could be arranged again on a concentric arc, as it is shown by dot-and-dash lines in Fig. 2. It is obvious that the compensating screws arranged on this larger arc and being therefore more remote from the oscillating spring a will have a smaller magnetic effect, which can be determined by tests, so that according to the error to be corrected, the magnetic screws can be screwed into tap holes of the inner or outer row or of both of the rows.

In some cases, the tap holes of the outer row could be made smaller than the tap holes of the inner row, so that smaller or larger magnetic screws having difierent magnetic strengths could be used for the above mentioned purpose. On the other hand, it would, of course, also be possible to use, in combination with the magnetic screws, non-magnetic screws made of a metal having a high magnetic permeability in order to reduce the magnetic eifect of the magnetic screws by influencing their magnetic flux.

Instead of being formed by screws the magnetic elements could also be formed by magnetic pins f (Fig. 3) for the reception of which the watch plate 0 would be .provided instead of tap holes with bored holes.

What I claim is:

1. A device for regulating, by way of magnetic influence, the temperature-coefficient of the oscillating system of a watch movement and the like, of the type having a self-compensating, ferro-magnetic oscillating spring, said device comprising a plate on which said spring is oscillatably journaled, said plate being provided in the neighborhood of said spring with a row of seats for the reception of magnetic elements, and a magnetic element seated in each of at least some of said seats, whereby a correction of the compensating error and therewith the regulation of said oscillating system may be effected.

2. The device recited in claim 1, said seats being constituted by tapped bores and said elements being constituted by magnetic screws.

3. The device recited in claim 1, said seats being arranged along an arc concentric with regard to the axis of the oscillating system.

4. The device recited in claim 1, said seats being arranged along a plurality of spaced arcs concentric with respect to the axis of the oscillating system.

REINHARD STRAUMANN. 

